fs/nilfs2/btnode.c

   1 /*
   2  * btnode.c - NILFS B-tree node cache
   3  *
   4  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * This file was originally written by Seiji Kihara <kihara@osrg.net>
  21  * and fully revised by Ryusuke Konishi <ryusuke@osrg.net> for
  22  * stabilization and simplification.
  23  *
  24  */
  25
  26 #include <linux/types.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/mm.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/gfp.h>
  31 #include "nilfs.h"
  32 #include "mdt.h"
  33 #include "dat.h"
  34 #include "page.h"
  35 #include "btnode.h"
  36
  37 void nilfs_btnode_cache_clear(struct address_space *btnc)
  38 {
  39         invalidate_mapping_pages(btnc, 0, -1);
  40         truncate_inode_pages(btnc, 0);
  41 }
  42
  43 struct buffer_head *
  44 nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
  45 {
  46         struct inode *inode = NILFS_BTNC_I(btnc);
  47         struct buffer_head *bh;
  48
  49         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
  50         if (unlikely(!bh))
  51                 return NULL;
  52
  53         if (unlikely(buffer_mapped(bh) || buffer_uptodate(bh) ||
  54                      buffer_dirty(bh))) {
  55                 brelse(bh);
  56                 BUG();
  57         }
  58         memset(bh->b_data, 0, i_blocksize(inode));
  59         bh->b_bdev = inode->i_sb->s_bdev;
  60         bh->b_blocknr = blocknr;
  61         set_buffer_mapped(bh);
  62         set_buffer_uptodate(bh);
  63
  64         unlock_page(bh->b_page);
  65         page_cache_release(bh->b_page);
  66         return bh;
  67 }
  68
  69 int nilfs_btnode_submit_block(struct address_space *btnc, __u64 blocknr,
  70                               sector_t pblocknr, int mode,
  71                               struct buffer_head **pbh, sector_t *submit_ptr)
  72 {
  73         struct buffer_head *bh;
  74         struct inode *inode = NILFS_BTNC_I(btnc);
  75         struct page *page;
  76         int err;
  77
  78         bh = nilfs_grab_buffer(inode, btnc, blocknr, 1 << BH_NILFS_Node);
  79         if (unlikely(!bh))
  80                 return -ENOMEM;
  81
  82         err = -EEXIST; /* internal code */
  83         page = bh->b_page;
  84
  85         if (buffer_uptodate(bh) || buffer_dirty(bh))
  86                 goto found;
  87
  88         if (pblocknr == 0) {
  89                 pblocknr = blocknr;
  90                 if (inode->i_ino != NILFS_DAT_INO) {
  91                         struct the_nilfs *nilfs = inode->i_sb->s_fs_info;
  92
  93                         /* blocknr is a virtual block number */
  94                         err = nilfs_dat_translate(nilfs->ns_dat, blocknr,
  95                                                   &pblocknr);
  96                         if (unlikely(err)) {
  97                                 brelse(bh);
  98                                 goto out_locked;
  99                         }
 100                 }
 101         }
 102
 103         if (mode == READA) {
 104                 if (pblocknr != *submit_ptr + 1 || !trylock_buffer(bh)) {
 105                         err = -EBUSY; /* internal code */
 106                         brelse(bh);
 107                         goto out_locked;
 108                 }
 109         } else { /* mode == READ */
 110                 lock_buffer(bh);
 111         }
 112         if (buffer_uptodate(bh)) {
 113                 unlock_buffer(bh);
 114                 err = -EEXIST; /* internal code */
 115                 goto found;
 116         }
 117         set_buffer_mapped(bh);
 118         bh->b_bdev = inode->i_sb->s_bdev;
 119         bh->b_blocknr = pblocknr; /* set block address for read */
 120         bh->b_end_io = end_buffer_read_sync;
 121         get_bh(bh);
 122         submit_bh(mode, bh);
 123         bh->b_blocknr = blocknr; /* set back to the given block address */
 124         *submit_ptr = pblocknr;
 125         err = 0;
 126 found:
 127         *pbh = bh;
 128
 129 out_locked:
 130         unlock_page(page);
 131         page_cache_release(page);
 132         return err;
 133 }
 134
 135 /**
 136  * nilfs_btnode_delete - delete B-tree node buffer
 137  * @bh: buffer to be deleted
 138  *
 139  * nilfs_btnode_delete() invalidates the specified buffer and delete the page
 140  * including the buffer if the page gets unbusy.
 141  */
 142 void nilfs_btnode_delete(struct buffer_head *bh)
 143 {
 144         struct address_space *mapping;
 145         struct page *page = bh->b_page;
 146         pgoff_t index = page_index(page);
 147         int still_dirty;
 148
 149         page_cache_get(page);
 150         lock_page(page);
 151         wait_on_page_writeback(page);
 152
 153         nilfs_forget_buffer(bh);
 154         still_dirty = PageDirty(page);
 155         mapping = page->mapping;
 156         unlock_page(page);
 157         page_cache_release(page);
 158
 159         if (!still_dirty && mapping)
 160                 invalidate_inode_pages2_range(mapping, index, index);
 161 }
 162
 163 /**
 164  * nilfs_btnode_prepare_change_key
 165  *  prepare to move contents of the block for old key to one of new key.
 166  *  the old buffer will not be removed, but might be reused for new buffer.
 167  *  it might return -ENOMEM because of memory allocation errors,
 168  *  and might return -EIO because of disk read errors.
 169  */
 170 int nilfs_btnode_prepare_change_key(struct address_space *btnc,
 171                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 172 {
 173         struct buffer_head *obh, *nbh;
 174         struct inode *inode = NILFS_BTNC_I(btnc);
 175         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 176         int err;
 177
 178         if (oldkey == newkey)
 179                 return 0;
 180
 181         obh = ctxt->bh;
 182         ctxt->newbh = NULL;
 183
 184         if (inode->i_blkbits == PAGE_CACHE_SHIFT) {
 185                 lock_page(obh->b_page);
 186                 /*
 187                  * We cannot call radix_tree_preload for the kernels older
 188                  * than 2.6.23, because it is not exported for modules.
 189                  */
 190 retry:
 191                 err = radix_tree_preload(GFP_NOFS & ~__GFP_HIGHMEM);
 192                 if (err)
 193                         goto failed_unlock;
 194                 /* BUG_ON(oldkey != obh->b_page->index); */
 195                 if (unlikely(oldkey != obh->b_page->index))
 196                         NILFS_PAGE_BUG(obh->b_page,
 197                                        "invalid oldkey %lld (newkey=%lld)",
 198                                        (unsigned long long)oldkey,
 199                                        (unsigned long long)newkey);
 200
 201                 spin_lock_irq(&btnc->tree_lock);
 202                 err = radix_tree_insert(&btnc->page_tree, newkey, obh->b_page);
 203                 spin_unlock_irq(&btnc->tree_lock);
 204                 /*
 205                  * Note: page->index will not change to newkey until
 206                  * nilfs_btnode_commit_change_key() will be called.
 207                  * To protect the page in intermediate state, the page lock
 208                  * is held.
 209                  */
 210                 radix_tree_preload_end();
 211                 if (!err)
 212                         return 0;
 213                 else if (err != -EEXIST)
 214                         goto failed_unlock;
 215
 216                 err = invalidate_inode_pages2_range(btnc, newkey, newkey);
 217                 if (!err)
 218                         goto retry;
 219                 /* fallback to copy mode */
 220                 unlock_page(obh->b_page);
 221         }
 222
 223         nbh = nilfs_btnode_create_block(btnc, newkey);
 224         if (!nbh)
 225                 return -ENOMEM;
 226
 227         BUG_ON(nbh == obh);
 228         ctxt->newbh = nbh;
 229         return 0;
 230
 231  failed_unlock:
 232         unlock_page(obh->b_page);
 233         return err;
 234 }
 235
 236 /**
 237  * nilfs_btnode_commit_change_key
 238  *  commit the change_key operation prepared by prepare_change_key().
 239  */
 240 void nilfs_btnode_commit_change_key(struct address_space *btnc,
 241                                     struct nilfs_btnode_chkey_ctxt *ctxt)
 242 {
 243         struct buffer_head *obh = ctxt->bh, *nbh = ctxt->newbh;
 244         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 245         struct page *opage;
 246
 247         if (oldkey == newkey)
 248                 return;
 249
 250         if (nbh == NULL) {      /* blocksize == pagesize */
 251                 opage = obh->b_page;
 252                 if (unlikely(oldkey != opage->index))
 253                         NILFS_PAGE_BUG(opage,
 254                                        "invalid oldkey %lld (newkey=%lld)",
 255                                        (unsigned long long)oldkey,
 256                                        (unsigned long long)newkey);
 257                 mark_buffer_dirty(obh);
 258
 259                 spin_lock_irq(&btnc->tree_lock);
 260                 radix_tree_delete(&btnc->page_tree, oldkey);
 261                 radix_tree_tag_set(&btnc->page_tree, newkey,
 262                                    PAGECACHE_TAG_DIRTY);
 263                 spin_unlock_irq(&btnc->tree_lock);
 264
 265                 opage->index = obh->b_blocknr = newkey;
 266                 unlock_page(opage);
 267         } else {
 268                 nilfs_copy_buffer(nbh, obh);
 269                 mark_buffer_dirty(nbh);
 270
 271                 nbh->b_blocknr = newkey;
 272                 ctxt->bh = nbh;
 273                 nilfs_btnode_delete(obh); /* will decrement bh->b_count */
 274         }
 275 }
 276
 277 /**
 278  * nilfs_btnode_abort_change_key
 279  *  abort the change_key operation prepared by prepare_change_key().
 280  */
 281 void nilfs_btnode_abort_change_key(struct address_space *btnc,
 282                                    struct nilfs_btnode_chkey_ctxt *ctxt)
 283 {
 284         struct buffer_head *nbh = ctxt->newbh;
 285         __u64 oldkey = ctxt->oldkey, newkey = ctxt->newkey;
 286
 287         if (oldkey == newkey)
 288                 return;
 289
 290         if (nbh == NULL) {      /* blocksize == pagesize */
 291                 spin_lock_irq(&btnc->tree_lock);
 292                 radix_tree_delete(&btnc->page_tree, newkey);
 293                 spin_unlock_irq(&btnc->tree_lock);
 294                 unlock_page(ctxt->bh->b_page);
 295         } else
 296                 brelse(nbh);
 297 }